1. Field of the Invention
The present invention relates to a hydraulic pressure control apparatus for an automatic transmission. More particularly, the present invention relates to a hydraulic pressure control apparatus for an automatic transmission that is provided with two oil pumps.
2. Description of Related Art
Generally, an automatic transmission includes a torque converter and a powertrain. In addition, the powertrain realizes multiple shifts by being connected with the torque converter. Further, a hydraulic pump (electric oil pump) is provided so as to supply operating pressure to the automatic transmission, and a TCU (transmission control unit) is provided so as to control operation of the automatic transmission.
Recently, a hydraulic pressure control apparatus for an automatic transmission having the two hydraulic pumps has been applied so as to enhance fuel consumption rate. A pressure of oil supplied from an oil tank is increased sequentially via the two hydraulic pumps in a hydraulic pressure control apparatus for an automatic transmission having the two hydraulic pumps. In addition, oil forms a low pressure portion via a hydraulic pump and oil forms a high pressure portion via the other hydraulic pump. Further, oil of the low pressure portion is supplied to a torque converter and a lubrication portion and oil of the high pressure portion is supplied to a powertrain so as to operate brakes and clutches.
Meanwhile, in a hydraulic pressure control apparatus for an automatic transmission having the two hydraulic pumps, when hydraulic pressure of the high pressure portion is deteriorated so as to supply hydraulic pressure to the low pressure portion, a load of the brakes and the clutches is generated and durability thereof is deteriorated.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.